Fine mapping and validation of a major QTL for grain weight on chromosome 5B in bread wheat.

Dehui Zhao,Jun Yan,Xiyue Song,Li Yang,Shuanghe Cao,Xianchun Xia,Zhonghu He,Jianqi Zeng,Dan Liu,Yong Zhang

doi:10.1007/s00122-021-03925-9

Abstract

A major QTL QTgw.caas-5B for thousand grain weight in wheat was fine mapped on chromosome 5B, and TraesCS5B02G044800 was predicted to be the candidate gene. Thousand grain weight (TGW), determined by grain length and width, and is an important yield component in wheat; understanding of the underlying genes and molecular mechanisms remains limited. A stable QTL QTgw.caas-5B for TGW was identified previously in a RIL population developed from a cross between Zhongmai 871 (ZM871) and a sister line Zhongmai 895 (ZM895), and the aim of this study was to perform fine mapping and validate the genetic effect of the QTL. It was delimited to an interval of approximately 2.0Mb flanked by markers Kasp_5B29 and Kasp_5B31 (49.6-51.6Mb) using 12 heterozygous recombinant plants obtained by selfing a residual BC1F6 line selected from the ZM871/ZM895//ZM871 population. A candidate gene was predicted following sequencing and differential expression analyses. Marker Kasp_5B_Tgw based on a SNP in TraesCS5B02G044800, the QTgw.caas-5B candidate, was developed and validated in a diversity panel of 166 cultivars. The precise mapping of QTgw.caas-5B laid a foundation for cloning of a predicted causal gene and provides a molecular marker for improving grain yield in wheat.

Highlights

Wheat is one of the most important food crops in the world, providing approximately 20% of the calories and 25% of the protein for humans (FAO 2017, http://www.fao.org/faostat/en/)
A stable quantitative trait loci (QTL) QTgw.caas-5B for Thousand grain weight (TGW) was identified previously in a RIL population developed from a cross between Zhongmai 871 (ZM871) and a sister line Zhongmai 895 (ZM895), and the aim of this study was to perform fine mapping and validate the genetic effect of the QTL
It was delimited to an interval of approximately 2.0 Mb flanked by markers Kasp_5B29 and Kasp_5B31 (49.6 Mb to 51.6 Mb) using 12 heterozygous recombinant plants obtained by selfing a residual BC1F4 line selected from the ZM871/ZM895//ZM871 population

Summary

Introduction

Wheat is one of the most important food crops in the world, providing approximately 20% of the calories and 25% of the protein for humans (FAO 2017, http://www.fao.org/faostat/en/). Yield is a complex quantitative trait determined by thousand grain weight (TGW), grain number per spike and spike number per unit area, with TGW having the highest heritability among three components (Simmonds et al 2014, 2016; Chen et al 2020; Yang et al 2020). With the current availability of genotyping arrays and release of wheat reference genome sequences (IWGSC, 2018; https://urgi.versailles.inra.fr/blast_iwgsc/) fine mapping of major QTL for TGW has been achieved using near-isogenic lines (NILs) and residual heterozygosity (Brinton et al 2017; Guan et al 2019; Xu et al 2019; Chen et al 2020)

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Conclusion